Jimmy Rollins and the Phillies sting the Nationals for a second consecutive night in Philadelphia, but the Braves capi­tal­ize this time with a 7-3 win in San Francisco to trim Washington NL East lead to 5 1/2 games. (Brian Garfinkel/Getty Images)

At the mention of the phrase “losing streak” late Saturday night, Ryan Zimmerman tilted his head back and covered his eyes, feigning dread in a mostly silent Washington Nationals clubhouse. Their 4-2 loss to the Philadelphia Phillies had led, minutes earlier in the same room, to a punched locker and a thrown hanger. But Zimmerman, after the Nationals lost their third straight, worked to conceal a smile.

“Three, ugh. I’m ready to quit,” Zimmerman sarcastically told a group of reporters. “Everything’s going to go into shambles.”

The Nationals remain on top of baseball even after their loss Saturday night at Citizens Bank Park, their 77-49 record still best in the majors. They surely know holding on to their status will prove just as hard as attaining it. They still have to face pitchers such as Roy Halladay, who on any night may be at his robotic best. They still have to respond to inevitable skids such as the three-game losing streak they are now in the middle of.

“You just battle through it,” first baseman Adam LaRoche said. “It doesn’t make it any easier if we come tomorrow thinking about tonight. We’ve been good all year about forgetting about it and coming back and getting another streak going. I don’t see how this will be any different.”

In his bid to earn his league-leading 17th win, Washington’s Gio Gonzalez gave up two runs before he recorded his second out. In the sixth, he yielded a game-winning home run to John Mayberry on the first pitch of the inning. Besieged this year by injury, Halladay returned to his dominant form with seven efficient innings. He threw 86 strikes in 105 pitches, with only a two-run, game-tying single by Steve Lombardozzi in the fifth saving a shutout.

The churn of the baseball season and the grind of a pennant race ensure nothing good will last forever and nothing will be as easy as it seems. Even the best teams, as the Nationals are suddenly finding, confront potholes to swerve around and rough patches to pull out of. You do not cruise into October. You have to earn it.

“There’s no way to go through a season without that,” Zimmerman said. “We just have to learn from our mistakes and keep playing good baseball. We’ve played good baseball. We just got beat the last two nights.”

Still, the Nationals have raised their stakes to where each loss matters. For a while in the Nationals’ clubhouse, only water smacking the floor, muffled curses and the squeaky wheels of carts pushed by clubbies interrupted silence.

Less than two weeks ago, the Nationals rolled through an eight-game tear, sustained winning that made you wonder how any team would beat them. Now they face their first three-game skid since July 21. The rarity of their losing streaks means they still hold a 51 / 2- game lead over the Atlanta Braves, who won Saturday afternoon in San Francisco to pick up a game in the standings.

“We’re really good at fighting back after we lose a couple,” LaRoche said. “We haven’t had that huge skid where everything falls apart. Again, I don’t see it happening here.”

The Nationals have lost the past two games as shortstop Ian Desmond and cleanup hitter Michael Morse continued to heal from injuries. Washington will miss them both Sunday, too, Manager Davey Johnson said. The offense, which mashed opposing pitchers as the Nationals went 8-2 on their West Coast trip this month, has averaged 2.7 runs over the past seven games.

“It’s not a lull,” Johnson said. “We just got a little beat up with Desi down and Morse down. Offense is just kind of not cooking. Could be the opposition pitching. It’s not chopped liver over there. They’ve very talented.”

The Nationals have lost only two series since the all-star break, both of those to Philadelphia. Now 171 / 2 games behind the Nationals, the Phillies are playing games only because the schedule dictates they must. But they still throw aces at you most nights. They still have pride.

“It’s important for us to play well against them, not only this year but going forward,” Halladay said. “They’re always going to be up there. Them and the Braves. It’s important for us to play well against them even in a season that hasn’t gone the way we want. It’s important to compete against those teams.

”I don’t think any of us are just going to roll over and give them games. We want to make a little bit of a statement. We still want to play. We still want to compete. We’re just not going to give anything away.”

It was a never a question of if the Nationals would avoid a blip. Their test will be how quickly they can snap it, and their pitching staff is well-suited for the task. They have not lost more than five straight all season. Even though Gonzalez, an all-star, couldn’t trump Halladay, Jordan Zimmermann and his 2.54 ERA will get a shot at Cliff Lee on Sunday afternoon.

“Hopefully that’s going to change it up for us a little bit,” Gonzalez said.

Gonzalez endured a rocky start. Like Edwin Jackson the night before, Gonzalez allowed the first three Phillies batters to reach base and allowed a run before the first ‘out’ light lit up on the scoreboard. The leadoff walk to Jimmy Rollins stung most. The flare to right and two grounders that became hits annoyed Gonzalez, causing him to kick dirt and look into the sky.

“At least I made the adjustment,” Gonzalez said. “After the first walk, they were swinging.”

Gonzalez settled down and restored his usual dominance, holding the Phillies scoreless for the next four innings. The Nationals tied the score for him in the fifth, and with one pitch he gave the Nationals another, final deficit. Gonzalez started the sixth inning with a 91-mph fastball to Mayberry, and he crushed it over the left field fence.

“Left it up, and he got it right over the wall,” Gonzalez said. “Can’t do nothing about it.”

The Nationals would go quietly in the ninth against closer Jonathan Papelbon, and the place erupted. Washington still has a comfortable lead in the NL East, but that does not mean closing it out will be easy.

“People forget that that’s a good team over there,” Zimmerman said. “I know they’ve traded some people away, but . . . we’ve got our work cut out for us. As far as a losing streak, I don’t anyone in here is panicking just yet. We’ll be okay.”